1) Field of the Invention
The present invention relates to a preprocessor of a division device, and in particular, to a preprocessor of a division device employing a high radix division system capable of producing a partial quotient of "n" bits (n.gtoreq.2) at a time (i.e., in a single processing step).
2) Description of the Related Art
A division operation is largely classified into three processes, namely: preprocess, main process, and postprocess. The preprocess is used to modify operand data into a form such that the main processor accepts the operand data, and the main process actually produces the quotient and a remainder. The postprocess modified the output of the main processor to produce a specified form of the main processor output, which is suitable as a result of the division output.
The preprocess of the division device has various forms, depending on the system of the main process. The most widely known system of the main process is a means such that one bit of a partial quotient is obtained by subtracting a divisor from a partial remainder, the result of such subtraction or the original partial remainder is shifted by one bit, and the resultant value is made a new partial remainder (hereinafter referred to as a "one-bit system"). The high radix division system is used to produce an n-bit partial quotient by a one time a processing (i.e., a single processing step), in comparison with the one-bit system.
The one-bit system performs a normalization shift, as a preprocess, to produce a significant bit of "1" both for a divisor and a dividend. Such a processing step is carried out by a preprocessor.
In the preprocessor of the division device as hereinbefore described, a drawback often arises when a high radix division requires both a quotient and a remainder at the same time. This is because an enumeration for obtaining a quotient must be stopped at the predetermined digit to leave a reminder, but such a predetermined digit is often not the last digit of a group of "n" digits.
Such a problem arises in the high radix division and therefore, conventionally, a dividend shift is performed after amending a micro program to make the bit number of the quotient, to be obtained, an integer multiple of "n".
However, such an amendment by the micro-program requires multiple machine cycles for the processing and, therefore, results in the deterioration in the performance of a division operation.